Frogs president Craig McCormack said the swims had start times that would allow participants to take part in all or a combination of the three distances.

Swimmers can register online for a flat fee of $10 for adults and $5 for under-18s.

There would also be swims of 500m, 250m and 125m. People involved in these events would not have to register, and would instead be asked to donate to Emu Park Surf Life Saving Club for its ongoing support of the Fitzroy Frogs.

McCormack said that with a contingent of swimmers making the trip down from Mackay, he would not be surprised to see 100 people hit the water on Friday.

"I'm expecting to see quite a few new faces, with people coming from different sports that involve swimming in some capacity," he said.

"Ocean swimming is an important leg within the triathlon event but the one people get to practise least.

"This event will give experienced swimmers a chance to fine-tune their technique and give novices the chance to try ocean swimming, confident in the knowledge there is adequate water safety in place and there are other people in the water around them."